This invention relates to a process for preparing organoclays and to the products of such a process.
An organoclay is an organophilic cation-modified clay derived from a clay mineral, generally of the smectite group, for example, bentonite, montmorillonite, hectorite, saponite or the like, by replacing the inorganic exchangeable cations, generally alkali or alkaline earth metal cations, which occur in the natural clay mineral, by organic cations each comprising at least one hydrocarbon radical which has sufficient carbon atoms to render the surface of the cation-exchanged clay hydrophobic.
Organoclays have been found to be very useful as thixotropic agents in organic media such as, for example, lubricating greases, oil-based drilling fluids, paints, varnishes, enamels and printing inks. However, an organoclay is, in general, difficult to disperse in an organic medium to form the uniform gel structure which is required to thicken, or to increase the viscosity of the organic medium. Even where sufficient dispersibility occurs to yield a satisfactory gel structure, small quantities of undispersed particles can be deleterious, such as in paints. Various means have been used to improve the dispersibility of an organoclay in an organic medium including the use of a polar organic material, such as a low molecular weight alcohol or ketone, as a dispersing aid, and the use of an excess of a specially selected organic cation in the preparation of the organoclay.
It is an object of the present invention to prepare an organoclay which has improved dispersibility as measured by the Hegman Gauge.
It is a further object of this invention to prepare an organoclay which will disperse readily in an organic medium to form a homogeneous gel structure.